A German man deported from the US has gone on trial in the Germany city of Mannheim for alleged Holocaust denial.
Rudolf denied that the Nazis used gas at death camps like Auschwitz
Germar Rudolf published a study saying the Nazis did not use gas to kill Jews at the Auschwitz concentration camp.
The prosecution says he "represented the Holocaust as invention" and used the internet to spread his documents.
If found guilty, Mr Rudolf will face up to five years in prison. He has already been given an jail sentence in a similar case but fled to the US.
A chemistry graduate, 42-year-old Mr Rudolf also faces charges of defaming the memory of the dead.
COUNTRIES WITH LAWS AGAINST HOLOCAUST DENIAL
He was sentenced to 14 months in prison in a similar case in 1995 but fled the country.
His 2000 application for political asylum in the US was rejected and he was deported back to Germany to serve the earlier sentence.
In a similar case in February 2005, British revisionist historian David Irving was found guilty of denying the Holocaust by an Austrian court and sentenced to three years in prison.